Video and audio compression methods have greatly contributed to the success of multimedia systems, such as the broadcast of digital television (TV) and streaming of Internet based video. Video compression methods reduce the amount of video data needed to store and transmit digital video images. Video compression methods have dramatically improved through the development of well-known International Telecommunication Union Telecommunication Standardization Sector (ITU-T) and International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) standards. One such standard, developed through the collaboration of ITU-T and ISO/IEC, is the H.264/Moving Picture Experts Group-4 (MPEG-4) Advance Video Coding (AVC). The H.264/MPEG-4 AVC standard has been widely adopted for many of today's video applications, such as high definition (HD) TV signals, real-time streaming videos, mobile applications, and BLU-RAY discs. However, modem communication and network systems are facing severe challenges as the video demand continues to increase with the diversification of video services, the emergence of beyond-HD video format, and the expectations for higher quality and resolution for a plethora of mobile devices.
The most recent video project by the ITU-T and ISO/IEC organizations is the development of the High Efficiency Video Coding (HEVC) standard. HEVC attempts to address infrastructure concerns by enhancing video resolution and implementing additional parallel processing architectures. In contrast to the H.264/MPEG-4 AVC standard, HEVC improves video quality and the data compression ratio while supporting resolutions up to 8,192×4,320. One way HEVC improves the coding efficiency of video content is by utilizing larger quantization matrices (QMs). For instance, HEVC may implement QMs up to a 32×32 block size, while the H.264/MPEG-4 AVC limits the quantization matrix (QM) block sizes to an 8×8 block size. Although larger QMs may enhance coding efficiencies, larger QMs, unfortunately, also produce larger overheads used to carry the QMs within a video bitstream, and thus cause bandwidth and capacity concerns.
In HEVC, a video picture may comprise twenty-four different QMs. The QMs associated with the video picture may have a variety of block sizes that include 4×4, 8×8, 16×16, and 32×32. The QM blocks associated with the video picture may correspond to intra/inter prediction types and luma/chroma (Y/Cb/Cr) color components. When encoding and storing the picture parameter sets (e.g. information such as picture size and optional coding modes) for a video picture, the number of matrix coefficients may equal 7,680 ((16*16+32*32)*2* 3) for the 16×16 and 32×32 QM blocks. Each coefficient may be about 8 bits long, and thus encoding the QM coefficients may produce an overhead of over 60,000 bits (7,680*8). A typical length for a compressed HD video frame may be about 50,000 to 500,000 bits in length. Hence, an overhead of over 60,000 bits to encode QM coefficients is too large to be encoded within a compressed video frame. Additionally, coding larger QMs (e.g. 32×32 QMs) using the AVC quantization matrix compression method found in the H.264/AVC standard (e.g. differential pulse code modulation (DPCM)) also produces an overhead that is substantially larger than a compressed HD video frame. Therefore, a more efficient coding method is needed to encode larger QMs.